Use of the bellows-type pressure responsive valve as a displacement control valve to be provided in a variable displacement compressor is disclosed in Japanese Publication No. 58-158382 of an unexamined Patent Application and Japanese Publication No. 5-52908 of an unexamined Utility Model Application.
The bellows-type pressure responsive valve comprises a bellows of a closed structure as a pressure sensing element, and is so constructed that expansions and contractions of the bellows are transmitted to a valve body by way of a valve rod which is supported on a valve housing so as to move in a valve lifting direction, to vary an opening amount of the valve. The bellows-type pressure responsive valve has such advantages as it is more compact and can take longer pressure responsive stroke than the diaphragm-type pressure responsive valve.
However, the bellows is generally difficult to be mounted in a straight line for structural and manufacturing reasons. In case where the bellows is weaving in the valve lifting direction, a lateral force is generated when expansions and contractions of the bellows take place in the valve lifting direction and transmitted to the valve rod, which incurs an increase of hysteresis, etc. in valve motions, resulting in a poor controlling performance and deterioration of accuracy of the valve motions.
In the above described Japanese Publication No. 5-52908 of the unexamined Utility Model Application, there is proposed an art that an end of the bellows and the valve rod are connected in a laterally slidable relation so as to absorb an axial displacement between axes of the bellows and the valve body by their mutual lateral slide. In this art, even though an axis of the bellows is offset from a center of a valve seat, an axis of the valve body is brought in alignment with the center of the valve seat.
However, in this art, only the offset of the axes in a lateral direction between the end of the bellows and the valve body can be compensated. When the bellows is weaving or inclined, the end of the bellows and the valve body come in an unsymmetrical abutment to cause unstable valve motions. Accordingly, the hysteresis in the valve motions cannot be refrained from increasing, but rather increases by loose motion of the end of the bellows in the laterally sliding portions.